Some of you may not like the solution (including me) but sometimes you need a little hack to make things work for you. In my case I required a constructor of property declared under custom namespace but not defined (null). Normally, you would go for describeType(), but guess what, yeah it just does not describes properties with namespace other than public. While there was nothing better in my mind than passing some unexpected value and expect what happend I decided to go for it. Luckily an exception was thrown with correct constructor name.

When creating flash / flex application for facebook, Application Type “Desktop” will work for you just fine, even when your app is deployed. My app is both embedded via iframe in facebook and standalone application (not in facebook). First I tought desktop mode is just to test my app locally and when finished, I should switch to web type. But guess what, after switching to “Web” type, my standalone application refused some actions (upload photos etc.), resulting in error:

error_code: 104
error_msg: Incorrect signature

So, I switched back to “Desktop” and both iframe and standalone applications works fine. 🙂 Correct me if I am wrong, but it seems, desktop application type works for facebook flash / flex api in all cases.